In a Los Angeles dungeon, she is known as Mistress Nina Payne. She is a professional dominatrix.

In real life, her name is Kimi Inch. She stumbled into a career in the world of BDSM -- short for bondage and discipline, sadism and masochism -- while working as a DJ in Japan.

She is now an expert in domination. Clients pay hundreds of dollars an hour to submit to her every whim, to be her "submissive" -- many BDSM participants use stage names. Inch meets them in the dungeon, where there are a variety of themed play rooms with names like "the vault" and "the parlor." Each one holds elaborate devices meant to restrain.

"There is so much more going on with BDSM. It's way more intense, way more intimate and way more psychological," Inch said. "I don't need to have sex with my clients in order to get them to that place."

Everything is negotiated ahead of time and is consensual, which is at the heart of BDSM, she said.

This is just one small part of the BDSM world, which is featured in "50 Shades of Kink," an episode from "Our America with Lisa Ling" on OWN television.

BDSM has been brought out of the shadows by the popularity of the book "50 Shades of Grey" and its sequels. Professionals like Inch are teaching regular people how to engage in non-standard sexual practices, called "kink," through giving group lessons in things like spanking.

"Instead of going in with a flat palm," she said to the audience. "I prefer to sort of slightly cup the hand, so it is actually going to sound like I'm hitting him a lot harder than I am, and that sound is going to stimulate him in many different ways."

Next Inch introduced the audience to another form of power exchange: letting someone tie you up. In the BDSM world, it's called rope play.

Between 15 to 20 percent of the American public has done something kinky in the bedroom, by some estimates, and the majority of those likely look like the couple next door. Keith and Monica, for example, are a happily married couple from a small New England town who also happen to practice BDSM.